Types of Chloramines

Chloramines are the topic of much conversation in aquatics nowadays. Chloramines are chemical byproducts of chlorine oxidizing bather waste (also known as the oxidant demand). They are referred to as disinfectant (or disinfection) byproducts (DBPs). Normally, it’s the incomplete oxidation of carbon, ammonia and nitrogen-based organic waste that creates chloramines.

As more and more hypochlorous acid (HOCl) is introduced to the water, chloramines progress through three stages: mono-chloramine (NH2Cl), di-chloramine (NHCl2), and tri-chloramine (NCl3). Trichloramines--another name for Nitrogen Trichloride--is the form that off-gasses to create indoor air quality (IAQ) problems for indoor pools. Due to the sheer amount of DBPs and the complex water chemistry involved, most of us in the industry loosely refer to all DBPs in pools as "chloramines" unless specified otherwise.

Believe it or not, chloramines actually have some disinfection ability, which is why they are also sometimes used as disinfectants in municipal water. Their health impact continues to be debated. That said, as more and more chlorine is added to the water, it begins to attack chloramines as though they are a part of the oxidant demand that must be destroyed in order to reach breakpoint chlorination.

At Orenda, we recognize the impact chloramines have on our health and comfort. We also believe there is no such thing as a single “cure” for all chloramine problems in pools. There are some great chemicals and systems that all address chloramines in different ways, and we believe it takes some of each to take control of a chloramine problem. This article gives our opinion on the strengths and weaknesses of chloramine solutions on the market today. That being said, our opinions are based on first-hand evidence from pools currently using these solutions.

Chemical solutions to chloramines

Traditionally, pool operators have been taught to measure their combined chlorine (total chlorine minus free chlorine). When the combined chlorine exceeds 0.2ppm, it’s time to shock the pool. Some use more free chlorine, like calcium hypochlorite (sometimes 10x the normal amount), and others use non-chlorine shock products like potassium monopersulfate (even though it’s not a sanitizer, just an oxidizer). The logic behind shocking is to reach breakpoint chlorination where partially burned up contaminants—like organic waste—get burned up completely.

Breakpoint chlorination is achieved after the oxidant demand has been destroyed.

A free available chlorine residual can only build after breakpoint has been reached.

There are a few issues with this. First and foremost, it takes a lot of chemicals—and they are not cheap—to shock a pool, and even more chemicals to restore balance afterward. For example, using a non-chlorine shock like potassium monopersulfate can reduce the pH in the pool, as well as leaving the byproduct of nitrates—which, like phosphates, are food for algae. Restoring balance takes more chemicals. Just look at all the problems that come with trying to beat chloramines with more chemicals. Second, it’s unclear if shocking actually solves the problem.

Shocking a pool, in our opinion, is to be used for disinfection purposes only--like a fecal incident or disease outbreak. Shocking for oxidation reasons should be a sign that normal chlorination is unable to handle your bather load.

Enzyme water treatment

As you may already know, our enzyme products break down and digest non-living organic waste to help chlorine be more efficient. In doing so, the amount of chloramines are reduced, since chlorine has a better chance at complete oxidation of organic waste. With the exception of fecal incidents at the pool, Orenda enzymes can drastically reduce the need to shock, if not eliminate it. Like anything, of course, there are always exceptions that depend on other factors.

Enzymes do not disinfect anything. They do not directly attack chloramines either—just their organic sources. Even in an enzyme-treated pool, some chloramines will still form and off-gas into the air, but the amount of them will be reduced.

Systems to eliminate chloramines

Waterborne chloramines

For waterborne mono- and di-chloramines, there may not be anything more effective at point-of-contact removal than UV. The problem is, UV is in the pump room, and has to wait for water to circulate through it. It can only kill what it sees, and if your pool has poor circulation or a high bather load (or both), UV may not be able to keep up. That said, it's incredibly effective at what it does.

An alternative to UV is ozone, which actually flows into the pool with a short lifetime. When set up and operated properly, ozone is an incredible oxidizer. The thing about ozone, however, is that it can be a strong irritant to humans. Ozone manufacturers have a de-gassing function on their systems, so the ozone does not get out into the air within the pool area. Despite de-gassing, it is difficult to guarantee that ozone will not off-gas in the breathing zone. But nevertheless, upon contact with waterborne chloramines, ozone can be very effective.

Airborne Chloramines

Inhalers are common at indoor pools with chloramine problems.

The most noxious chloramines of all are tri-chloramines. These are the ones that go airborne and cause all sorts of problems for people and the facility itself. Airborne chloramines are very acidic, and when combined with moisture already in the air—from pool evaporation—they condense on metals, causing rampant rust, corrosion and overall destruction. The problems really compound in indoor pools, where HVAC systems either recirculate chloramines, or they get trapped in the bottom of the natatorium—in the swimmer’s breathing zone—unable to escape.

Tri-chloramines and other DBPs destroy HVAC systems, metal structures (like a roof or structural steel), and metal pool equipment, such as starting blocks, lights or timing equipment. Pool chemicals and systems to treat waterborne chloramines are useless against airborne tri-chloramines (obviously). To address airborne chloramines, there is only one system that we have seen to be truly effective: The Evacuator, by Paddock. It’s a ventilation system that targets and exhausts the harmful air in a pool, and prevents HVAC systems from recirculating it. We have seen several indoor pools with Evacuator systems, and they are very effective.

Like every other ‘solution’ to chloramines, there are weaknesses of the Evacuator system too. First, unless its design was coordinated before the pool was built—Evacuator built into the pool gutter or deck drain, matching the HVAC system design—its effectiveness is at the mercy of the shape and design of the room. Retrofit Evacuators can still be a huge improvement to air quality, but may not be able to fully solve the problem. Second, putting one in an existing pool is a significant capital investment. Third, the Paddock Evacuator will not fit in every facility; many require a redesign of their current duct and HVAC system.

Ideal defense against chloramines

As we said earlier, we at Orenda do not believe that any one “solution” can completely eliminate chloramine problems. Be wary of any brand or product that claims otherwise, because this problem is not black and white. There are a multitude of factors to address, and we believe that the healthiest pool environment requires the following:

Chlorine sanitizer

Hyperchlorinate (shock)only when absolutely needed. Like during a fecal incident.

Secondary disinfection system. This could be UV or Ozone, though we have found that UV has less maintenance and is very effective. Outdoor seasonal pools may not have as much of a need for this, since they have natural sunlight on their side.

Enzymes. Yes, we’re biased, and we’re not ashamed of it. We wouldn’t even make our product if we didn’t believe it was worth using. We stand behind Orenda enzymes because we know how effective they are.

Evacuator system for indoor pools only. Since there is only one company that makes this product—Paddock—if you have an airborne chloramine problem, contact them to see if your pool is eligible for what they do.

As for pool chemistry, our dosing calculator is a great tool for you to know how much of each chemical to put in your pool. Thousands of operators use it every day.

Conclusion

Chloramines are inevitable, but can be reduced and controlled. Be wary of any company or brand that claims they have “the answer”. For example, Paddock’s Evacuator only handles airborne chloramines, not those in the water. UV only kills what flows through the UV system, and nothing in the air. Enzymes don’t even eat chloramines; they break down non-living organic waste to give chlorine less work to do…therefore more complete oxidation…meaning less byproducts in the pool.

Mono- and di-chloramines will become tri-chloramines and become airborne if they’re not addressed fast enough. They are harmful to people, buildings, and can be very costly. Doing nothing is simply unacceptable as a pool operator. Your patrons depend on you to provide them a healthy experience.